Bitcoin UTXO and Change Addresses
concept
Core idea
Bitcoin transactions consume inputs and create outputs. A spend sends value to a recipient, the miner takes a fee, and any remainder returns to the sender as change, often to a different address still controlled by the sender (an unspent transaction output, or UTXO). Reading inputs and outputs correctly is essential to avoid mistaking change for a payment to a third party.
When to use
When tracing Bitcoin and you see multiple outputs on a transaction and must decide which is the real payment and which is change back to the sender.
Example
Think of a vending machine: you feed in a 10 dollar note from your right pocket (input), buy a sandwich (the spend), and put the change in your left pocket (a different address, still yours). On mempool.space a transaction can show one input, a spend output, a fee, and a change output returning to the sender.
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